Figure 1: N to P ratios in relation to latitude.
From: Global-scale latitudinal patterns of plant fine-root nitrogen and phosphorus
(a) Root N:P ratios are best described by the power regressions (Φ<1 mm: y=55.7×latitude−0.366, r2=0.379, n=111, blue circles with blue trend line; 1≤Φ<2 mm: y=34.1×latitude−0.324, r2=0.188, n=374, green circles with green trend line; 2≤Φ<5 mm: y=56.6×latitude−0.463, r2=0.484, n=74, red circles with red trend line; Φ≥5 mm: y=90.1×latitude−0.562, r2=0.575, n=47, yellow circles with yellow trend line; and dead roots: y=66.6×latitude−0.420, r2=0.305, n=34, pink circles with pink trend line) and (b) green-leaf N:P ratio (data from references6,8) is best described by a linear function (y=28.2–0.334×latitude, r2=0.174, n=903, green circles with green trend line), and senesced-leaf N:P ratio (data from references8,9) is best described by a power function (y=122.3×latitude−0.547, r2=0.284, n=636, yellow circles with yellow trend line), all relationships are significant at P<0.0001.
